Peter and Rosemary Grant study natural selection in finches on the Galápagos Islands. They found that dry
condition produce larger seeds and may result in larger beaks in succeeding generations of finches. The figure below shows their data from 1976 (wet year) and 1978 (dry year). The y-axis is the number of birds measured and the x-axis is the beak depth. The average beak depth of birds in the population increased from 8.8mm in 1976 to 9.8mm in 1978. What type of selection is this?
E. Negative frequency-dependent